Rapid drug susceptibility testing and treatment outcomes for multidrug-resistant tuberculosis in Peru

Factors associated with unfavorable treatment outcomes in patients with rifampicin-resistant tuberculosis in Colombia 2013-2015: A retrospective cohort study

Background

Multidrug- and rifampicin (RMP)-resistant tuberculosis (MDR/RR-TB) requires prolonged and expensive treatment, which is difficult to sustain in the Colombian health system. This requires the joint action of different providers to provide timely health services to people with TB. Identifying factors associated with unfavorable treatment outcomes in patients with MDR/RR-TB who received drug therapy between 2013 and 2015 in Colombia can help guide the strengthening of the national TB control program.

Method

A retrospective cohort study was conducted with all patients who received treatment for MDR/RR-TB between January 2013 and December 2015 in Colombia who were registered and followed up by the national TB control program. A multivariate logistic regression model was used to estimate the associations between the exposure variables with the response variable (treatment outcome).

Results

A total of 511 patients with MDR/RR-TB were registered and followed up by the national TB control program in Colombia, of whom 16 (3.1%) had extensive drug resistance, 364 (71.2%) had multidrug resistance, and 131 (25.6%) had RMP monoresistance. The mean age was 39.9 years (95% confidence interval (CI): 38.5–41.3), most patients were male 285 (64.6%), and 299 (67.8%) were eligible for subsidized health services. The rate of unfavorable treatment outcomes in the RR-TB cohort was 50.1%, with rates of 85.7% for patients with extensive drug resistance, 47.6% for patients with multidrug resistance, and 52.6% for patients with RMP monoresistance. The 511 MDR/RR-TB patients were included in bivariate and multivariate analyses, patients age ≥ 60 years (crude odds ratio (ORc) = 2.4, 95% CI 1.1–5.8; adjusted odds ratio (ORa) = 2.7, 95% CI 1.1–6.8) and subsidized health regime affiliation (ORc = 3.6, 95% CI 2.3–5.6; ORa = 3.4, 95% CI 2.0–6.0) were associated with unfavorable treatment outcomes.

Conclusion

More than 50% of the patients with MDR/RR-TB in Colombia experienced unfavorable treatment outcomes. The patients who were eligible for subsidized care were more likely to experience unfavorable treatment outcomes. Those who were older than 60 years were also more likely to experience unfavorable treatment outcomes.

Impact of Molecular Drug Susceptibility Testing on the Time to Multidrug-resistant Tuberculosis Treatment Initiation

BACKGROUND

The purpose of this study was to evaluate the current status and trends in the coverage of molecular drug susceptibility testing (mDST), and the impact of mDST on the time to multidrug-resistant tuberculosis (MDR-TB) treatment initiation in Korea.

METHODS

We included confirmed rifampin-resistant (RR)/MDR-TB patients who submitted application forms for novel drug uses to the National TB Expert Review Committee from September 1, 2016 to November 30, 2019. We retrospectively reviewed their medical records.

RESULTS

Of the 621 MDR/RR-TB patients, mDST was performed in 442 (71.2%); Xpert MTB/RIF (Xpert) alone in 109 (17.6%), MTBDRplus line probe assay (LPA) alone in 199 (32.0%), and both Xpert and LPA in 134 (21.6%) patients. The coverage rate of mDST has gradually increased to 70% in 2015, 50.7% in 2016, 67.9% in 2017, 75.2% in 2018, and 79.4% in 2019 (P for trend < 0.001). Median time to MDR-TB treatment initiation was 35 days (interquartile range_25-75 0-72), which has gradually decreased during the study period (P < 0.001). Independent predictors of shorter time to MDR-TB treatment initiation were retreatment case (adjusted hazard ratio [aHR], 1.30; 95% confidence interval [CI], 1.10-1.54), Xpert testing (aHR, 2.42; 95% CI, 2.03-2.88), and LPA testing (aHR, 1.83; 95% CI, 1.55-2.16). Transfer to another healthcare facility was inversely related to shorter time to treatment initiation (aHR, 0.74; 95% CI, 0.63-0.88).

CONCLUSION

mDST coverage is gradually increasing and contributes to reducing the time to MDR-TB treatment initiation. Further efforts are needed to achieve universal access to mDST and to properly integrate mDST into routine clinical practice.

Mutations in Mycobacterium tuberculosis Isolates with Discordant Results for Drug-Susceptibility Testing in Peru

Evaluation of resistance to antituberculosis drugs is routinely performed with genotypic or phenotypic methods; however, discordance can be seen between these different methodologies. Our objective was to identify mutations that could explain discordant results in the evaluation of susceptibility to rifampicin and isoniazid between molecular and phenotypic methods, using whole genome sequencing (WGS). Peruvian strains showing sensitive results in the GenoType MTBDRplus v2.0 test and resistant results in the proportions in the agar-plaque test for isoniazid or rifampin were selected. Discordance was confirmed by repeating both tests, and WGS was performed, using the Next Generation Sequencing methodology. Obtained sequences were aligned “through reference” (genomic mapping) using the program BWA with the algorithm “mem”, using as a reference the genome of the M. tuberculosis H37Rv strain. Discordance was confirmed in 14 strains for rifampicin and 21 for isoniazid, with 1 strain in common for both antibiotics, for a total of 34 unique strains. The most frequent mutation in the rpoB gene in the discordant strains for rifampicin was V170F. The most frequent mutations in the discordant strains for isoniazid were katG R463L, kasA G269S, and Rv1592c I322V. Several other mutations are reported. This is the first study in Latin America addressing mutations present in strains with discordant results between genotypic and phenotypic methods to rifampicin and isoniazid. These mutations could be considered as future potential targets for genotypic tests for evaluation of susceptibility to these drugs.

[Loss to follow-up in patients treated for multidrug-resistant tuberculosis in EcuadorA Perda de seguimento de pacientes tratados para tuberculose multirresistente a medicamentos no Equador]

OBJECTIVE

Determine the incidence of loss to follow-up (LTFU) in patients treated for rifampicin-resistant tuberculosis (RR-TB) or multidrug-resistant tuberculosis (RR/MDR-TB), and the factors associated with this discharge status in Ecuador.

METHODS

Retrospective cohort study of patients with RR/MDR-TB who followed the World Health Organization's 18-24-month treatment regimen in 2014 and 2015, as reported by the Ministry of Health of Ecuador. The incidence of LTFU was determined, and clinical and epidemiological manifestations of cases discharged as LTFU were compared with those discharged as successfully treated. Survival was analyzed with Cox regression in order to evaluate factors associated with LTFU.

RESULTS

Of 328 cases, 270 (82.3%) were analyzed because they had a reported discharge status. Discharge as LTFU accounted for 39.6% of cases, and as successfully treated, 50.4%. The risk factors associated with LTFU were: previous discharge as LTFU in a previous TB episode [hazard ratio (HR): 2.96 (1.53-5.73), P < 0.001]; addiction to alcohol or drugs [HR: 2.82 (1.10-7.23), P = 0.031]; and having an Xpert® diagnosis (TB-RR) [HR: 1.53 (1.0-2.35), P = 0.048]. Of the total LTFU, 43% occurred after nine months of treatment.

CONCLUSION

The incidence of LTFU in patients with RR/MDR-TB in Ecuador is above the average for the Region of the Americas. The three identified factors support implementation of shorter regimens and patient-centered care, in line with the End TB Strategy.